Systems and methods for optically powering transducers and related transducers

ABSTRACT

The present disclosure describes an optically powered transducer with a photovoltaic collector. An optical fiber power delivery method and system and a free space power delivery method are also provided. A fabrication process for making an optically powered transducer is further described, together with an implantable transducer system based on optical power delivery.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 61/236,024, filed on Aug. 21, 2009, which is incorporated herein byreference in its entirety.

STATEMENT OF GOVERNMENT GRANT

The U.S. Government has certain rights in this invention pursuant toGrant No. HR0011-04-1-0054 awarded by DARPA.

FIELD

The present disclosure relates to transducers. More particularly, thepresent disclosure relates to systems and method for optically poweringtransducers and related transducers.

SUMMARY

According to a first aspect, an optically powered transducer isprovided, comprising: a sensor circuitry adapted to convert anenvironmental or ambient signal of interest into a sensor electricalsignal; an electronic circuitry adapted to process the sensor electricalsignal; and a photovoltaic collector adapted to collect optical energy,convert the optical energy to electrical energy and power the sensorcircuitry and the electronic circuitry with the electrical energy.

According to a second aspect, a method for fabricating an opticallypowered transducer is provided, comprising: fabricating a sensorcircuitry and an electronic circuitry on a transducer substrate, saidtransducer substrate being on top of a sacrificial layer; fabricating aphotovoltaic collector on the transducer substrate, the photovoltaiccollector adapted to adapted to collect optical energy, convert theoptical energy to electrical energy and power the sensor circuitry andthe electronic circuitry with the electrical energy; providing acommunication light source on the transducer substrate; and releasingthe sacrificial layer.

According to a third aspect, a fiber optic power delivery system isprovided, comprising at least one monitoring system; at least oneoptical fiber; and at least one transducer adapted to be opticallypowered by the at least one monitoring system through the at least oneoptical fiber.

According to a fourth aspect, a method for optically powering atransducer is provided, comprising directing optical energy at thetransducer through an optical fiber.

According to a fifth aspect, a method for powering an optically poweredtransducer is provided, comprising directing optical energy at theoptically powered transducer in absence of an optical fiber arrangement.

According to a sixth aspect, a method for exchanging information with atleast one optically powered transducer is provided, comprising: poweringthe at least one optically powered transducer by directing opticalenergy at the optically powered transducer; establishing a wireless datalink with each of the at least one optically powered transducers; andexchanging information with each of the at least one optically poweredtransducers through the wireless data link.

Further embodiments of the disclosure are provided in the specification,drawings and figures of the present application.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of thepresent disclosure and, together with the description of exampleembodiments, serve to explain the principles and implementations of thedisclosure.

FIG. 1 shows a top view and a cross-section view of an optically poweredtransducer, in accordance with an embodiment of the present disclosure.

FIG. 2 shows micro-fabricated resonant cavities, suitable for thetransducers of FIG. 1.

FIGS. 3A-3C show views of a photovoltaic collector suitable to be usedwith the optically powered transducer in accordance with an embodimentof the present disclosure.

FIG. 4 shows electrical power output versus input optical power diagramsmeasured from photovoltaic collectors fabricated with CMOS-compatibleprocesses, in accordance with an embodiment of the present disclosure.

FIG. 5 shows an example of a CMOS laser driving circuit suitable to beused with the optically powered transducer of FIG. 1.

FIG. 6 shows a fabrication process of an optically powered transducer,in accordance with an embodiment of the present disclosure.

FIG. 7 shows a fiber-based power delivery system for an opticallypowered transducer, in accordance with an embodiment of the presentdisclosure.

FIG. 8 shows a free space power delivery scheme for an optically poweredtransducer, in accordance with an embodiment of the present disclosure.

FIG. 9 shows an implantable transducer system, in accordance with anembodiment of the present disclosure.

FIG. 10 shows wavelength-dependent absorption loss in blood and tissue.

DETAILED DESCRIPTION

Throughout the specification, the term “photovoltaic collector” refersto a device/component/apparatus that collects optical energy and convertthe optical energy to electrical energy. For example, a photovoltaiccollector may be a silicon-based P-N junction. A person having ordinaryskill in the art would understand that a photovoltaic collector may befabricated with other materials and the material for a photovoltaiccollector may be selected to achieve different target conversionefficiencies in different situations.

FIG. 1 shows a top view (100) and a cross-sectional view (120) of anoptically powered transducer, in accordance with an embodiment of thepresent disclosure. In this embodiment, the optically powered transduceris powered by optical energy. With sufficient power, the opticallypowered transducer measures or picks up signals of environmentalinterest (e.g., blood sugar concentration, and neuron electricpotential). The optically powered transducer then transmits data that isindicative of the signals of interest wirelessly. The signaltransmission may be optical or other electromagnetic waves (e.g., WiFi,and Bluetooth®).

With continued reference to FIG. 1, the optically powered transducercomprises a photovoltaic collector (102), an electronic circuitry (108),and a sensor circuitry (110). According to a further embodiment of thepresent disclosure, the optically powered transducer further comprises acommunication light source (106) that may transmit optical dataindicative of the signals of interest (e.g., blood sugar concentration).In a still further embodiment, the communication light source (106) maycomprise a laser, or a light-emitting diode.

The photovoltaic collector (102) collects optical energy, converts theoptical energy into electrical energy and powers the electroniccircuitry (108), the communication light source (106), and the sensorcircuitry (110). In another embodiment of the communication light sourcemay directly collect optical energy and powers itself. The sensorcircuitry (110) measures or picks up environmental signals of interest,such as pressures, light, temperatures, RF electromagnetic waves, etcand converts signals of interest into electrical signals. The electroniccircuitry (108) processes the signals from the sensor circuitry (110)and drives the communication light source (106) to transmit lightsignals indicative of the environmental signals of interest picked up bythe sensor circuitry (110).

According to an embodiment of the present disclosure, the photovoltaiccollector (102) collects optical energy and powers the optically poweredtransducer. By way of example, the photovoltaic collector (102)comprises resonant cavities (104) and one or more photovoltaicjunctions. The resonant cavities are located surrounding thephotovoltaic junctions. According to a further example, the resonantcavities (104) comprise high finesse cavities. The resonant cavities(104) may increase the effective photon path length and photonabsorption efficiency of the photovoltaic junctions. In addition, theresonant cavities (104) or other surface gratings may divert incominglight vertically incident to the photovoltaic slab (the material thatabsorbs light and converts it into electric current) into the in-planedirection (the direction parallel to the original wafer surface).According to another embodiment of the present disclosure, aphotovoltaic collector with resonant cavities has a smaller size thanone with no resonant cavity. FIG. 2 shows micro-fabricated resonantcavities, in accordance with an embodiment of the present disclosure.According to a further embodiment, vertical cavities can be provided toincrease the collection efficiency. Such cavities are typically calledFabry-Perot resonators with dielectric or metallic minors deposited ontop and bottom of the p-n junction.

According to an embodiment of the present disclosure, the short circuitcurrent density in a monochromatic (laser illuminated) photovoltaiccollector isJ _(SC) =q·N·QE,  (1)where q is electronic charge, N is density of incident photons (q·N isthe incident charge density/photon energy) and QE is (external) quantumefficiency. In theory, maximum available output power density can begiven by product of the maximum output voltage (open circuit voltage,V_(OC)), and the maximum available current density (short circuitcurrent density, J_(SC)). However, in practice, it is not possible toobtain that maximum power because of loading effects. Usually, a fillfactor is defined to illustrate the effect of the load on the cell. Thefill factor can be described by the following equation:

$\begin{matrix}{{FF} = {\frac{J_{MX} \cdot V_{M}}{J_{SCX} \cdot V_{OC}}.}} & (2)\end{matrix}$where J_(M) and V_(M) are the current density and the output voltage atthe maximum power point. Therefore, the maximum output power densitywould beP _(M) =V _(MX) ·J _(M).  (3)P_(M) is often represented in terms of cell characteristics asP _(M) =FF _(X) ·V _(OCX) ·J _(SC),  (4)and conversion efficiency can be defined as

$\begin{matrix}{\eta = {\frac{P_{M}}{P_{in}} \cdot 100.}} & (5)\end{matrix}$

By way of example, not of limitation, TABLE 1 shows calculation resultsof efficiencies and output power for an input power density of 10mW/cm². Calculations of the Best Case are based on the followingassumptions: QE=95%; junction ideality factor n=1; and J_(M)=95% ofshort circuit current density. In addition, series resistance isapproximated as the diode resistance of the cell and shunt resistance isignored. For the Practical Case, calculations are based on the followingassumptions: QE=65%; junction ideality factor n=1.5; transmissioncoefficient=0.9 (0.9² for power transmission coefficient).

TABLE 1 P_(in) P_(out) P_(in) (mW/cm²) (mW/cm²) (mW) P_(out) (mW)Efficiency Best Case 10 4.8 0.2 0.095 48% Practical Case 10 3.1 0.20.061 31% Best Case: QE = 0.95, n = 1, Rs = rs/A, rs = VT/Jsc, A = 2mm². Practical Case: QE = 0.65, n = 1.5, Rs = rs/A, rs = VT/Jsc, A = 2mm².

FIGS. 3A-3C show views of a photovoltaic collector suitable to be usedwith the optically powered transducer in accordance with an embodimentof the present disclosure. The cell of FIG. 3A is a photovoltaic cellconstructed by a standard CMOS process in a silicon foundry.

FIG. 4 shows electrical power output versus input optical power diagramsmeasured from photovoltaic collectors fabricated with CMOS-compatibleprocesses. The figure is taken from André W. and Martel S.,“Micro-photovoltaic cells designed for magnetotaxis-based controlledbacterial microrobots,” IEICE Electronics Express, Vol. 5 (2008), No. 3pp. 101-106, which is incorporated herein by reference in its entirety.The photovoltaic collectors have very linear current-power relationship.Indeed, the current extracted from the photovoltaic collector islinearly dependent on the incident power of light over a large range ofincident power densities, far beyond the ones shown in the case ofphotovoltaic collectors in FIG. 4 with ˜0.25 W/cm². At 0.25 W/cm², 50 μAcan be generated from a 400×400 μm photovoltaic collector, and 30 μA isgenerated in a 200×400 μm photovoltaic collector. In a furtherembodiment, the photovoltaic collectors can be irradiated with up to 10kW/cm² (over 4 orders of magnitude above the power levels shown in FIG.4) before the P-N junction in the photovoltaic collector becomessaturated with carriers and no longer acts as a p-n junction. Thisimplies that the photovoltaic collector can be further reduced in size.Thermal effects may ultimately limit the conversion efficiency of suchphotovoltaic collectors far before kW/cm² power densities are reached.By pulsing with higher power densities of kW/cm², the area for powergeneration can be significantly reduced, promising furtherminiaturization of the optically powered transducer.

By way of example and not of limitation, the sensor circuitry (110) ofthe optically powered transducer of FIG. 1 may be an implantablepressure sensor, a medical implant, a blood sugar detector, anautonomous sensor, a humidity sensor, a gas sensor, a pathogen sensor, alight sensor, a stress or strain sensor, a motion sensor, etc.

There are several methods for measuring blood sugar optically. Thesimplest is by observing the change in the refractive index of the serumor plasma. Increased sugar content will increase that refractive index.However, also the amount of water in the body will change the refractiveindex. Such kind of test could be used for monitoring rapid changes inthe blood glucose level. Another way of measuring the blood sugaroptically is through absorption spectroscopy, in which the opticalincident light excites some vibrational modes of the sugar molecules(dextrose, glucose, etc) and these increase the absorption proportionalto the amount of sugar in the blood. A third way to measure the bloodsugar is through Raman spectroscopy, in which light at high intensityexcites the sugar molecules, and light that is shifted (typically tolower energy) comes out of the illuminated region. That additional lightcan be measured with a filtered detector and the difference in energybetween the emitted light and the pump light can be very specific to thevibrational modes that have been excited in the sugar molecules.Resonant Raman measurements provide the most specific opticalmeasurement of blood glucose.

According to another embodiment of the present disclosure, theelectronic circuitry (108) of FIG. 1 may also include a capacitor orother energy storage component. The electrical energy generated from thephotovoltaic collector (102) may be stored in the capacitor or otherenergy storage component. The stored electrical energy may be used topower the sensor circuitry (110) and the electronic circuitry (108).Optionally, the stored electrical energy may be used to drive thecommunication light source (106).

In a still further embodiment, the electronic circuitry (108) of FIG. 1comprises a circuitry that controls the communication light source (106)of the optically powered transducer. According to another embodiment ofthe present disclosure, the electronic circuitry (108) may containprograms or information that defines the transducer's functions and makethe transducer wireless.

According to an embodiment of the present disclosure, the electroniccircuitry (108) of FIG. 1 processes the output from the sensor circuitry(110). By way of example, not of limitation, the electronic circuitry(108) may comprise CMOS silicon circuits that perform amplification andamplitude-to-pulse-width conversion. With these circuits, the electroniccircuitry (108) may amplify the output from the sensor circuitry andmodulate the output according to an amplitude-to-pulse-width conversion.The electronic circuitry (108) may also comprise a driving circuitrythat drives the communication light source (106). The electroniccircuitry (108) can be fabricated in silicon by CMOS processing by usingappropriate mask sets, tested while still on the wafer, and subsequentlyremoved from its original substrate.

FIG. 5 shows an example of a CMOS laser driving circuit suitable to beused with the optically powered transducer of FIG. 1.

With reference to FIG. 1 again, the communication light source (106) canprovide the optically powered transducer with a wireless, optical datalink to other devices. The communication light source (106) can beeither a light emitting diode or a semiconductor laser. According to afurther embodiment, the communication light source (106) may serve asthe light source for spectroscopic measurements. For example, acommunication laser may also be the light source for refractive indexmeasurements for blood sugar monitoring application.

In particular, the blood sugar measuring examples mentioned above withthe refractive index, the absorption and the Raman measurement, may beperformed by lasers in the near-infrared, e.g. by changing laseremission wavelength or laser intensity, or by emitting additionalwavelengths. Therefore, the same laser that transmits the power to thedevice or the one that performs the data communications function canalso be used to perform the optical spectroscopy test.

The communication light source (106) may be powered by the photovoltaiccollector (102). In another embodiment, the communication light source(106) may collect optical energy by itself and powers itself. This canbe done by direct optical pumping close to the threshold values of thecommunication light source).

In particular, the light (incident light in the near-infrared) used toconvert into photo-current for the photovoltaic collector can be usedfor an additional purpose of exciting carriers in the on-chip laser onthe autonomous system. These carriers in turn generate light (i.e.photoluminescence) in that laser. That laser starts to emit light at itsresonant frequency—i.e. it is an optically pumped laser. At this point,if it is desired to use the laser to transmit information, all what isneeded is to turn the laser off rather than on. This is calledQ-switching, and can be done electrically. Therefore, such embodimentmay be useful in terms of power, as there is no need to supply the powerfor the on-chip laser from the photovoltaic power generator, as thepower can be laser based on photoluminescence with the abundant externallight that needs to be there anyway for the photovoltaic generator.

FIG. 6 shows a fabrication process of an optically powered transducer,in accordance with an embodiment of the present disclosure. According tothis embodiment, the fabrication starts with preparing (612) atransducer substrate (602) on top of a sacrificial layer (604). Forexample, the transducer substrate (602) and the sacrificial layer (604)are selected to be compatible with silicon-based CMOS processingtechnologies.

Next, the photovoltaic collector (608), the electronic circuitry, andthe sensor circuitry are fabricated (614) on the transducer substrate(602). These components can be fabricated with CMOS-compatibleprocessing technologies.

Next, a communication light source (608) is placed (616) on thetransducer substrate (602). For example, the communication light sourcecan be placed by wafer bonding technologies. The optically poweredtransducer may be tested before the final releasing. Then, the opticallypowered transducer (610) is released (618). The optically poweredtransducer (610) has a size ranging from 10 microns to 500 microns.

Fiber-optics provides high-bandwidth communications between deviceswithin optical systems. Many modern platforms are equipped with fiberoptic communication systems. Such fiber optic systems are typicallyoptimized for low dispersion and minimal absorption loss operation atbandwidths in excess of several gigabits per second. The bandwidthavailable within these fiber optic systems is often underutilized, ashigh frequency fiber communications is optimized for small spectralregions with low-loss wavelength “bands.”

FIG. 7 shows a fiber-based power delivery system, in accordance with anembodiment of the present disclosure. According to this embodiment, thefiber power delivery system (700) comprises at least one monitoringsystem (706), at least one optical fiber (704), and at least oneoptically powered transducer (702). In a further embodiment, the fiberpower delivery system (700) distributes power and sensing/monitoringsignals through a spectral region different from that used by ahigh-speed fiber optic communication system.

Examples of such monitoring systems can include a broader version of thesame approaches described above in the blood glucose case. If, forexample, a chemical with a specific absorption resonance in theatmosphere or in a water sample is to be measured, the chemical can bebound to the surface of a fiber-based detection system, and measured byobserving the refractive index (through changes in resonance wavelengthof our laser or a cavity), the absorption (through changes in currentfrom our photovoltaic power supply), or through the intensity of theRaman-shifted light (by looking at the spectrum of light coming backthrough the fiber). By way of example, the same chips that are describedas implanted devices can be used, bonded to the end of a fiber, andambient chemistry rather than blood chemistry can be measured.

The optically powered transducer (702) receives power from themonitoring system (706) through the optical fiber (704). In a furtherembodiment, the optically powered transducer (702) communicates with themonitoring system at low bit rates. In a further embodiment, theoptically powered transducer (702) collects the optical power with aphotovoltaic collector. As explained with reference to FIG. 1, thephotovoltaic collector of the optically powered transducer (702) mayhave resonant cavities. Powered by an optical fiber, the opticallypowered transducer (702) does not need to use extra electricalconnections for power delivery. Communicating at lower bit rates mayreduce ambient influences (e.g. temperature and humidity) on theoptically powered transducer's sensitivity.

According to another embodiment of the present disclosure, the opticallypowered transducer (702) may compare signals from other parts of thenetwork and reduce false positive alarm rates by looking for a trend toconfirm whether the device is working or not.

According to an embodiment of the present disclosure, the fiber powerdelivery system uses as optical power sources monochromatic high-powerpump lasers at 850 nm or 980 nm.

FIG. 8 shows a free space power delivery scheme, in accordance with anembodiment of the present disclosure. In this embodiment, an opticallypowered transducer (802) is powered by incoming light (808) from amonitoring system (806). No optical fiber is used. According to afurther embodiment, the optically powered transducer (802) may transmitinformation to the monitoring system (806) or other device throughoutgoing light (810) from the optically powered transducer's opticalcommunication source (e.g. vertical or lateral cavity lasers).

If desired, the optically powered transducer (802) can be placed in amedium (804). The medium (804) may be animal or human body tissues(804). In another embodiment, the optically powered transducer may beplaced in other media, such as oil, water, etc. Power delivery andsignal transmission would not be obstructed as long as the medium (804)has sufficiently high transmission at the light wavelength the opticallypowered transducer (802) uses. For example, human body tissues have lowabsorption at light wavelength longer than 700 nm. Therefore, light witha wavelength of around 850 nm can be used for power delivery and signaltransmission.

According to a further embodiment of the present disclosure, theoptically powered transducer (802) may comprise the electronic circuitryand/or the sensor circuitry of the optically powered transducer ofFIG. 1. As usual, if desired, these circuitries may be fabricated withCMOS-compatible processing technologies.

Because the optically powered transducer is small (e.g., from severalmillimeters to several microns in lateral dimensions) and because nooptical fiber is used, the free space power delivery scheme is useful inmedical implant applications or other applications that require smallvolumes. For example, the free space power delivery scheme may be usefulfor monitoring fuel tanks, determining mechanical strain in structuralelements and free-space communications within systems, like militarysystems.

FIG. 9 shows an example of an implantable transducer system. In thisembodiment, an optically powered transducer (904) is implanted in ananimal or human tissue (902). The optically powered transducer (904) ispowered optically by an external reader (906). With sufficient power,the optically powered transducer (904) communicates with an externalreader (906) wirelessly.

In accordance with an embodiment of the present disclosure, theoptically powered transducer (904) may comprise the components of thetransducer recited with reference to FIG. 1, including a photovoltaiccollector, an electronic circuitry, and a sensor circuitry.

The optically powered transducer (904) remains inactive after its storedpower is used up. To communicate with the optically powered transducer(904) (e.g., reading measurements), the reader (906) directs opticalenergy (908) at the optically powered transducer (904). The opticallypowered transducer (904) “wakes up” when light shines on it. As thetransducer recited with reference to FIG. 1, the photovoltaic collectorof the optically powered transducer (904) collects the optical energy(908) and powers up the electronic circuitry and the sensor circuitry ofthe optically powered transducer (904). The optically powered transducer(904) then communicates with the reader via a wireless data link (910),performs its designated operation (e.g. measuring blood sugarconcentration via the sensor circuitry), transmitting measurementinformation, etc. When the optically powered transducer (904) finishesits operations or uses up its stored energy, it goes to an inactive ordormant state again. The wireless data link (910) comprises, forexample, an optical data link. A person having ordinary skill in the artshould understand that other wireless data links, such as Bluetooth® andWiFi, may be used.

In accordance with an embodiment of the present disclosure, the reader(906) generates optical energy with a near-IR semiconductor laser with awavelength between 680 nm and 980 nm. FIG. 10 shows wavelength-dependentabsorption loss in blood and tissue. The curve (1002) represents theabsorption of 7% blood; the curve (1004) 75% water and the curve (1006)total. A low tissue absorption window starts around 700 nm. Thus, anear-IR semiconductor laser with a wavelength around 750 nm to 980 nmcould efficiently provide optical energy through tissues up to severalcentimeters thick. In addition, near IR wavelengths may provideefficient photon-electron conversion and little heating on a siliconsubstrate. A person having ordinary skill in the art would understandthe fabrication, design and use of a near-IR semiconductor laser. Aperson having ordinary skill in the art would also understand that thereader (1006) may use other light sources emitting wavelengths, e.g.from 800 to 1600 nm, such as around 850 nm and/or 980 nm. Alsowavelengths around 1300 or 1500 nm can be used.

According to an embodiment of the present disclosure, the reader (906)may optically power and read many optically powered transducers at thesame time and communicate each transducer with a specific laserwavelength or electronic signal signature

The examples set forth above are provided to give those of ordinaryskill in the art a complete disclosure and description of how to makeand use the embodiments of the systems and methods for opticallypowering transducers and related transducers of the disclosure, and arenot intended to limit the scope of what the inventors regard as theirdisclosure. Modifications of the above-described modes for carrying outthe disclosure may be used by persons of skill in the art, and areintended to be within the scope of the following claims. All patents andpublications mentioned in the specification may be indicative of thelevels of skill of those skilled in the art to which the disclosurepertains. All references cited in this disclosure are incorporated byreference to the same extent as if each reference had been incorporatedby reference in its entirety individually.

It is to be understood that the disclosure is not limited to particularmethods or systems, which can, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting. As used in this specification and the appended claims, thesingular forms “a,” “an,” and “the” include plural referents unless thecontent clearly dictates otherwise. The term “plurality” includes two ormore referents unless the content clearly dictates otherwise. Unlessdefined otherwise, all technical and scientific terms used herein havethe same meaning as commonly understood by one of ordinary skill in theart to which the disclosure pertains.

A number of embodiments of the disclosure have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the presentdisclosure. Accordingly, other embodiments are within the scope of thefollowing claims.

We claim:
 1. An optically powered transducer, comprising: a sensorcircuitry adapted to convert an environmental or ambient signal ofinterest into a sensor electrical signal; an electronic circuitryadapted to process the sensor electrical signal; a multi-functionallight source adapted to a) support an optical data communications linkbetween the optically powered transducer and at least one anotherdevice, and b) provide light for performing optical spectroscopy; and aphotovoltaic collector adapted to collect optical energy, convert theoptical energy to electrical energy and power the sensor circuitry andthe electronic circuitry with the electrical energy.
 2. The opticallypowered transducer according to claim 1, wherein the optical datacommunications link is adapted to transmit a signal indicative of theenvironmental or ambient signal of interest.
 3. The optically poweredtransducer according to claim 2, wherein the photovoltaic collector isfurther adapted to power the multi-functional light source with theelectrical energy.
 4. The optically powered transducer according toclaim 2, wherein the multi-functional light source comprises alight-emitting diode or a semiconductor laser.
 5. The optically poweredtransducer according to claim 2, wherein the multi-functional lightsource is adapted to emit light at a wavelength selected from around 850nm, around 980 nm, around 1300 nm or around 1500 nm.
 6. The opticallypowered transducer according to claim 1, further comprising at least oneoptical resonator adapted to increase absorption efficiency of thephotovoltaic collector.
 7. The optically powered transducer according toclaim 6, wherein the at least one optical resonator comprises at leastone resonant cavity.
 8. The optically powered transducer according toclaim 1, wherein the sensor circuitry is at least one of an implantablepressure sensor, a blood sugar detector, a medical implant, anautonomous sensor, a humidity sensor, a gas sensor, a pathogen sensor, alight sensor, a stress sensor, a strain sensor, or a motion sensor. 9.The optically powered transducer according to claim 1, wherein theelectronic circuitry further comprises an energy storage apparatusadapted to store the electrical energy converted by the photovoltaiccollector.
 10. The optically powered transducer according to claim 1,wherein the electronic circuitry is further adapted to controloperations of the optically powered transducer.
 11. The opticallypowered transducer according to claim 1, wherein the electroniccircuitry further comprises a circuit selected from a CMOS amplificationcircuit, a CMOS amplitude-to-pulse-width conversion circuit, or a CMOSlaser driving circuit.
 12. The optically powered transducer according toclaim 1, wherein the sensor circuitry is operative as a blood sugardetector and wherein performing optical spectroscopy comprises at leastone of refractive index, absorption or Raman measurements.
 13. Theoptically powered transducer according to claim 1, wherein a firstwavelength of the multi-functional light source is changed to a secondwavelength when performing optical spectroscopy.
 14. The opticallypowered transducer according to claim 1, wherein the multi-functionallight source is a multi-wavelength light source for performing opticalspectroscopy using multiple wavelengths.
 15. A method comprising:powering an optically powered transducer by directing optical energy atthe optically powered transducer; using a light source located in theoptically powered transducer to enable an optical data link; and usingthe light source to provide light for performing optical spectroscopy.16. The method according to claim 15, wherein the directing opticalenergy comprises providing optical energy of wavelength between around800 nm and around 1600 nm.
 17. The method according to claim 15, whereinusing the light source to provide light for performing opticalspectroscopy comprises changing a wavelength.
 18. The method accordingto claim 15, wherein using the light source to enable the optical datalink comprises using a first wavelength of light, and using the lightsource to provide light for performing optical spectroscopy comprisesusing a second wavelength.